#define LDR A5
#define LED 3

int sensor_value,output_value;

void setup() {
  // put your setup code here, to run once:

  pinMode(LED, OUTPUT);
  
}

void loop() {
  // put your main code here, to run repeatedly:
  
  sensor_value=analogRead(LDR);
  output_value=map(sensor_value,0,1023,1023,0);
  analogWrite(LED,output_value/4);
  //delay(500);

}